1. Field of the Invention
The present invention relates to a crawler belt for use on a crawler motor vehicle.
2. Description of the Prior Art
Generally, crawler belts have a flat and wide surface area for contact with a road, and hence apply a relatively low pressure from the flat and wide surface area to the road. When a crawler motor vehicle with such crawler belts runs on a road which is wet with rain or the like, the frictional force between the crawler belts and the road, i.e., the grip of the crawler belts, tends to be lowered, resulting in reduced traction. Such a disadvantage is aggravated by the tendency for the crawler belts to fail to discharge water from recesses in their road contact surfaces. Therefore, the crawler belts are required be improved to achieve running stability on wet roads, muddy roads, snow-covered roads, and icy roads. The higher the grip of the crawler belts, the better the running stability thereof.
One conventional crawler belt proposed in Japanese laid-open utility model publication NO. 3-103506 has a pattern of ridges on its outer circumferential surface, i.e., its road contact surface. The pattern of ridges includes rib-like ridges and lug-like ridges arrayed on the road contact surface of the crawler belt. Specifically, the crawler belt has arrays of rib-like ridges on its center and arrays of lug-like ridges on its opposite ends, and side guides on the reverse side for preventing the crawler belt from being dislodged from the wheels around which it is trained.
Grooves defined in the road contact surface of the disclosed crawler belt are generally surrounded by adjacent ones of the ridges. Therefore, water or mud cannot easily be discharged from the grooves, particularly from those grooves which are located in the central region of the crawler belt, when the crawler belt is running on a wet road or a muddy road. Consequently, the conventional crawler belt also suffers a relatively small frictional force between itself and the road, i.e., a small grip, and cannot apply desired traction.
The lug-like ridges are of a rectangular cross-section having a rectangular edge profile in the transverse direction of the crawler belt. When the rectangular edges of the lug-like ridges hit surface irregularities of the road or are caught by grooved trails of the road while the crawler belt is running on the road, the crawler belt tends to lose its running stability, particularly, its straight running stability. In addition, when the rectangular edges of the lug-like ridges hit surface irregularities of the road, the crawler belt is liable to produce vibration and noise called road noise.
While a crawler motor vehicle with crawler belts trained around drive and idle wheels is running on rough terrain, the crawler belts thereof tend to be elastically deformed by ground surface irregularities, causing the drive and idle wheels to be disengaged from the crawler belts.
There has thus been a demand for improved crawler belts for higher running stability.